[Program information (data, reports, photographs) can be found on the internet at: http://www.uark.edu/campus-resources/cotinus/arboretum_html/planteval.html]

January 2006

This completes the seventh year of the statewide plant evaluation program. The current team of cooperators includes Dr. Jim Robbins, Dr. Jon Lindstrom, and Manjula Carter.

The three test sites are the Hope Research Center (USDA cold hardiness zone 8), Little Rock (zone 7a), and the Fayetteville Horticulture Research farm (zone 6b). As much as possible the three test sites were prepared in a similar manner. Full sun plants were grown in row-type beds 3’ wide with a 7’ grass alley. Plant groups are planted together (i.e. trees are planted together). Trees are spaced 10’ apart, shrubs 6’ apart, and herbaceous perennials 4’ apart. The Little Rock site was planted on April 29, 2005; Fayetteville was planted on May 9, 2005; Hope planted on April 14, 2005. Irrigation at all three sites is by a drip system. Plants were fertilized and mulched after planting. Post-emergent herbicides were used at all three test sites. No disease or insect control was implemented during the first year. To maintain a tree-like habit, trees are pruned following final growth measurements. Pruning consists of removing the bottom 1/3 of limbs. SHRUBS are NOT pruned. Final growth measurements were taken at Little Rock on October 10; Fayetteville on October 13; and Hope on October 19.

Note: Significant losses occurred with the 2004 planting. Several frosts and freezes occurred after planting date and these weather occurrences had a significant, detrimental effect on many of the plants as noted below.

One-gal plants were initiated by the UofA from plants at the University of Georgia . Plants are growing well statewide with no plant losses in 2005. Plants were noted to flower at Hope in early August. Average plant size is 31" tall x 20" wide and a year-end growth index (GI) of 0.162 m³.

One-gal plants were initiated by UofA from a plant from the U.S. National Arboretum. Plants are growing very well at Hope and Little Rock but not Fayetteville. All 4 plants died at Fayetteville during the first growing season. Flowering started at Hope on May 3 and ended on May 20. Average plant size at Little Rock and Hope is 12" tall x 189" wide and a year-end growth index (GI) of 0.052 m³.

One-gal plants of were initiated by cuttings at UofA from Stephen F. Austin Arboretum plants. Plants are doing well at Hope and Little Rock with no plant losses recorded. Plants are struggling at Fayetteville. Plants started flowering at Hope on April 28 and finished on May 10. Average plant size is 31" tall x 28" wide and a year-end growth index (GI) of 0.338 m³.

One gallon plants were initiated by John Kirby. In general, growth was good at all three locations. Plants have done fairly well statewide. One plant died at Hope and Little Rock. The full sun exposures at the trial locations does not seem ideal for this yellow foliaged plant. Average plant size is 13" tall x 5" wide and a year-end growth index (GI) of 0.004 m³.

One gallon plants were initiated by cuttings at UofA from Dr. Lindstrom’s breeding program. Plants have performed exceptionally well statewide. Plants are very uniform across the three sites. Plants began flowering at Hope in mid-June and continued until late October. Average plant size is 32" tall x 47" wide and a year-end growth index (GI) of 1.008 m³.

One gallon plants were initiated by cuttings at UofA from a Forestfarm Nursery plant. Plants have performed well statewide with no mortality in the first year. Average plant size statewide is 35" tall with a trunk caliper of 0.5".

One quart plants were purchased from Forestfarm Nursery. Considering how small the plants were, plants have performed well. Two plants have died at Hope and Little Rock, respectively. Average plant size statewide is 24" tall with a trunk caliper of 0.3".

The Ornamentals team would like to express their sincere appreciation to the cooperating nurseries ( Dr. Michael Dirr- University of Georgia and Dr. David Creech, Stephen F. Austin Arboretum) for donating the plants for this season’s trial and to the Arkansas Green Industry Association for financial support.